A method of controlling a message output from a system to a user is known. For example, JP-A 10-320093 (KOKAI) discloses a technique that adjusts the timing of message output according to the property of the message and the state of a user. In addition, JP-A 2009-110038 (KOKAI) discloses a technique that presents information to a user when the user is in a state in which the information can be presented, and stands-by for the presentation when the user is in a state in which the information cannot be presented.